In recent times, the type of flow meter known as the coriolis force flow meter has been successfully developed wherein a U-tube or a 360 degree loop of tube containing moving fluid is oscillated in a direction perpendicular to the plane including the loop of the tube or U-tube on the plane of symmetry dividing the U-tube or a loop of tube into two equal halves and the torque or torsion about an axis coinciding with the line of intersection between the plane including the loop of the tube and the plane of symmetry dividing the loop of the tube into two equal halves is measured to indicate the time rate of mass flow of the fluid through the loop of the tube. Although the coriolis force type flow meter is accurate and reliable when it is used to measure reasonably low rates of flow of a liquid medium, it has been unsuccessful to measure the flow rates of gaseous media or fluid flow at a very low rate. The flow of a gaseous medium does not generate a precession torque large enough to be detected by a coriolis force flow meter using a vibrating loop of tube, while the aforementioned type of flow meter is not suitable to measure the flow rate of fluid at a high flow rate in terms of difficulties encountered in the construction and operation thereof.
Although many inventors and engineers pioneering the art of the coriolis flow meter technology have failed to understand the operating principles thereof, it is quite clear that a coriolis force flow meter operates in the same principle as the mechanics of a spinning top. When the spinning axis of a spinning top deviates from a perfectly vertical axis, the spinning top nutates about the vertical axis while it spins about its own spinning axis. A coriolis force flow meter with a greater sensitivity and broader applicability can be constructed in structures utilizing the mechanics of the spinning top.
The primary object of the present invention is to provide a precession flow meter operating on principles similar to the mechanics of spinning tops.
Another object is to provide a precession flow meter including a conical shell with a fluid inlet disposed at the diverging extremity thereof wherein a plurality of radially disposed spiral flow quides impose spinning movement on the fluid entering therethrough.
A further object is to provide a precession flow meter including a fluid outlet disposed at the converging extremity of the conical shell.
Yet another object is to provide a precession flow meter including means disposed at the converging extremity of the conical shell for imposing oscillatory movements of the converging extremity relative to the diverging extremity thereof on a first plane including the central axis of the conical shell.
Yet a further object is to provide a precession flow meter including means for measuring the amplitude of the vibratory movements of the converging end of the conical shell taking place on a second plane including the central axis of the conical shell and perpendicular to the first plane on which the oscillatory movement is imposed.
Still another object is to provide a precession flow meter including means for converting the amplitude of the vibratory movement of the converging extremity of the conical shell on the second plane to the mass flow rate of the fluid passing through the conical shell.
Still a further object is to provide a precession flow meter wherein the converging extremity of the conical shell is oscillated at a resonance frequency of the vibrating system including the conical shell and the fluid moving therethrough.
These and other objects of the present invention will become clear as the description thereof proceeds.